1. Field of the Invention
The present invention relates generally to thermal protection circuits and, more specifically to thermal protection circuits for semiconductor dies.
2. Background Art
A System-On-Chip (SOC) typically includes an integrated electronic system on a single integrated circuit (IC) chip. As transistor size continues to shrink in submicron SOCs, transistor leakage power can correspondingly increase. Since transistor leakage power is a function of temperature, as the temperature of the SOC increases, the leakage power can also increase. When heat generated as a result of the leakage power and the active power from the SOC exceeds the heat dissipation capacity of the SOC package, chip temperature can rise at a faster rate with increasing leakage power, thereby resulting in a process called “thermal runaway.” Since a thermal runaway can destroy the SOC by causing it to burn up, it is very important to prevent the thermal runaway from occurring.
In a conventional approach for preventing a thermal runaway from occurring, a thermal diode can be built into the SOC. A separate thermal sensor chip residing on the circuit board that houses the SOC can then read the temperature of the SOC from the on-chip thermal diode and generate over temperature alarm and control signals to shut down the power supply to the SOC or put the SOC in a low power mode so as to prevent thermal runaway. In this conventional approach, however, thermal diode offset and noise from the SOC can undesirably limit the accuracy of the temperature measurement. Accordingly, there is a need in the art for providing effective thermal runaway protection for an IC chip, such as an SOC.